Fuel Supply Problem

[johnrmclean]

Well a new problem. Running home yesterday my 1994 ..454 Baja was running fine at about 3500 RPM . Approaching home I decided to throttle back to about 1000 RPM and just run back in slow. When I throttled down it died out on me. It sputtered a couple times on cranking at first then nothing and I could not get it started. I did not think it was getting any fuel so I pulled off the fuel filter/water separator and the fuel level in it was down about 1/2 inch from the top. I dumped it to make sure there was no water in it then replaced it. After considerable cranking with nothing I pulled it again and it had minimal fuel in it. I never got it restarted. I suspect the fuel pump crapped out. Any thoughts??

 

[Scott Danforth]

you dumped the contents and replaced with new, or you reused the filter (they are not reusable without contaminating the clean side)

there are stickies at the top of the forum for testing the fuel pump

 

[alldodge]

Well a new problem. Running home yesterday my 1994 ..454 Baja was running fine at about 3500 RPM . Approaching home I decided to throttle back to about 1000 RPM and just run back in slow. When I throttled down it died out on me. It sputtered a couple times on cranking at first then nothing and I could not get it started. I did not think it was getting any fuel so I pulled off the fuel filter/water separator and the fuel level in it was down about 1/2 inch from the top. I dumped it to make sure there was no water in it then replaced it. After considerable cranking with nothing I pulled it again and it had minimal fuel in it. I never got it restarted. I suspect the fuel pump crapped out. Any thoughts??

Agree, either the fuel pump or anti-siphon valve. Try the remote fuel tank and see if it will fill the filter

 

[johnrmclean]

There is nothing wrong with the fuel. Just dumped the filter to check for sure and first thing to check on the way back from the carb.. Fuel was clean and no H2O or debris re-primed the filter. Checked the anti siphon valve on the tank and it definitely seemed stuck and I thought that must be the problem so replaced it with a new one today. ..still no luck.... it would not pump up fuel on its own..I was finally able to get it started by spraying some fuel directly into the carb and was able to throttle the engine up and down but after about 5 minutes idling when I tried to do that again it died and I could not get it restarted even by spraying some fuel in the carb....what next??? Note ..The new valve was definitely better than the the old one but I did notice it was still not really easy to blow through as I anticipated.

 

[johnrmclean]

Questions: what are the "stickies" your noted for testing? I do not have a remote fuel tank ..do you mean set up a remote tank to see if it will fill?

 

[Fun Times]

Questions: what are the "stickies" your noted for testing?

The helpful stickies are full of past info to help make troubleshooting a bit easier on you. They are located at the top of iboats main engine model discussion technical forums.
Here's a direct link to the starting of them. MUST HAVE Technical Information for DIYers.

 

[alldodge]

A remote fuel tank is where you remove the fuel line from the tank and stick it inside a gas can. This way the fuel tank and pickup tube is taken out of the equation.

Your pump should be mounted on the seawater pump, and unless the rubber fuel line has collapsed internally, then its probably the pump. Your part number is 861677T ($200) and is made by Airtex 60932 ($60)

**Note** the Airtex cross reference number states its for 92-93 carb and EFI motors. That said my 95 7.4 and 94 7.4/8.2 uses the same Airtex pump. Currently have the Airtex on my 95, and had it on my 94 but removed when the motor was rebuilt and went to electric

 

[johnrmclean]

Thanks all..

 

[KJM]

the air vent to your tank could be clogged, try her with the gas filler cap off.

 

[johnrmclean]

Pretty sure the vents wide
open but will check it

 

[johnrmclean]

Update ..well now that I have the boat out of the water and started to winterize I have pulled the carb and fuel pump off the engine.

The carb looks good and there was very little fuel in it. What was in it had a dark yellow color for some reason. I took the fuel feed line off and as I look into the opening I see a small strainer/filter that sticks up into the center of the inlet. It looks good, not dirty or clogged but will have to take the carb apart to check from inside the carb.

The fuel pump might look questionable. It did have fuel in it but when I removed it the cam cavity below the pump was filled with fuel. Not sure if some of that leaked in there as i removed the pump. There is a plastic line that comes from the carb to the lower side of the pump and enters below the diaphragm side of the pump. This tube and the entry port into the pump were plugged solid at the pump. I assume this is a vent tube of some sort but not sure what function it has or how being plugged might effect performance. After taking the pump apart I see the area under the diaphragm is quite dirty. Not sure if replacing it will solve my problems but for the money , about $88.00 its going to happen.

 

[Scott06]

Tube to carb is a safety feature so when the diaphragm in the pump ruptures it doesn't dump fuel into the bilge, tube pushes it up and dumps it in the carb. Will most likely cause and over rich situation but prevent a fire hazard. Was ther fuel in the hose? If the was plugged could have prevented the diaphragm from pumping properly, I'd replace it based on what you describe here

 

[alldodge]

pump was filled with fuel

Your pump is bad and can be fixed or replaced as in post 7

 

[johnrmclean]

Welcome to the 2017 boating season. I'm just now getting my boat out and back to my fuel problem from last year. The fuel pump was toasted and I installed a new pump today but I noticed the cam wheel on the drive shaft for the water pump that the fuel pump's pump lever rides on just spins freely on the shaft. I'm thinking that's not right and it can't possibly actuate the pump. If so the water pump assembly is probably bad. Any feed back out there?

Thanks

 

[alldodge]

There is a ring over the cam pump shaft. In the link below item 15 is the shaft with a cam lobe and item 16 is the ring your noticing. The ring acts like a bearing and lets the cam slide under it in gear lube.

Note: remember to check the gear lube to determine if the pump ever starts leaking gas. Fill the pump cavity to the top screw hole

http://www.mercruiserparts.com/bam/subassembly/31802/1621/330

 

[johnrmclean]

Ok so that answers that . So the pump should be good however the next issue then is although I have replaced the fuel pump I'm cranking but not getting any fuel into the carb. Is there a trick to get the fuel line primed and gas flowing?

 

[alldodge]

There is no trick, it should self prime. Connect a line from the pump to a gas can.

Was there any gear lube in the pump housing when old pump was removed?

 

[johnrmclean]

Thanks for that feed back . I pre filled the water separator and got the fuel pump installed per your suggestions and its pumping fuel to the carb, a webber, but I'm not getting any fuel out of the carb into the engine. Can't even smell a sniff of gas. Suggestions?

 

[alldodge]

If you remove the fuel line and get fuel coming out of it and not the carb, then need to get into the carb. Your going to need to get into the carb or replace it. Take the fuel line off then remove the top of the carb and see whats inside

 

[johnrmclean]

yep fuel line has fuel coming out but not carb so I guess the carb comes back off tomorrow.